The invention relates to rod making machines of the tobacco processing industry, especially to cigarette rod making and filter rod making machines. More particularly, the invention relates to improvements in wrapping mechanisms for use in rod making machines of the above outlined character. The following description will refer primarily to cigarette rod making machines with the understanding, however, that the invention can be embodied with equal advantage in wrapping mechanisms of machines which are designed to make other rod-shaped tobacco-containing products as well as rod-like articles which contain filter material for tobacco smoke.
The wrapping mechanism of a cigarette rod making machine (e.g., a machine known as PROTOS which is made and distributed by the assignee of the present application) employs a first endless belt conveyor (known as garniture) which cooperates with stationary guide means to gradually convert a continuously supplied web of cigarette paper or other suitable wrapping material into a tube and to simultaneously drape the web around a continuous rod-like tobacco-containing filler. The latter is supplied by a second endless belt conveyor which is preferably permeable to air so that tobacco particles can be caused to adhere thereto by suction in a manner well known from the art of cigarette making. As a rule, that reach or stretch of the second conveyor which delivers the filler defines a downwardly sloping path terminating in the region where the web of wrapping material undergoes a curling or analogous deforming action to be converted into a tube which is thereupon sealed by adhesive to confine the rod-like filler and to advance the resulting cigarette rod toward a cutoff or another suitable device serving to subdivide the rod into plain cigarettes of unit length or multiple unit length. It is presently preferred to feed a shower of tobacco particles upwardly within a duct having a discharge end at the underside of the lower reach of the second belt conveyor; the tobacco particles are converted into a stream which contains a surplus of tobacco and such stream is thereupon trimmed or equalized by removing the surplus of fibrous material. The trimmed stream constitutes the filler and is advanced into the range of the wrapping mechanism. The upper reach of the first belt conveyor is horizontal, the same as that portion of the web of wrapping material which is delivered onto and is shaped by the first conveyor.